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Alain wrote:
> nemesis nous apporta ses lumieres en ce 03/05/2006 12:35:
>> "LEO_BOLOGNA" <l_o### [at] yahoo it> wrote:
>>
>>> it seems that there isn't any support for nurbs in povray! is it
>>> possible?
>>
>>
>> Someone correct me if i'm wrong, but i believe bicubic patches are
>> exactly
>> that. They are one of povray primitives and they describe surfaces via
>> control points which are interpolated by a spline. Isn't Non-Rational
>> Uniform B-Splines just that?...
>>
>> Povray has a long history and many names do not correspond exactly to the
>> ones popular today. For instance, people looking for a "Global
>> Illumination" feature will likely not link Radiosity to it...
>>
>>
>>
> Sory, bicubic patch are not nurbs and don't behave like nurbs. They are
> more like arays of bicubic splines.
>
AFAIK, Non-Rational Bicubic B-Splines (NURBS is singular, so would the
plural be NURBSes?) is the popular name for what used to be popularly
known as Bezier patches, named for the researcher who first published
them (although they were previously developed by someone working for the
Army, who did not permit him to publish his work so I don't remember his
name). Mathematically, they're bicubic splines, so this is the name
that POV-Ray used originally. NURBS, as a name, is just a little more
specific (specifying that they are non-rational, and the specific type
of spline).
Where most people get confused, is that many graphical modelling
programs create arrays of NURBS, and hide the control points from the
user, so they don't actually know what's going on under the hood. The
POV-Ray syntax (which was never meant to be hand-written, per the
documentation) requires the declaration of all 16 control points.
...Chambers
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